81739570 has 32 divisors (see below), whose sum is σ = 169952256. Its totient is φ = 27974400.

The previous prime is 81739513. The next prime is 81739571. The reversal of 81739570 is 7593718.

It is not an unprimeable number, because it can be changed into a prime (81739571) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19986 + ... + 23725.

It is an arithmetic number, because the mean of its divisors is an integer number (5311008).

Almost surely, 2^81739570 is an apocalyptic number.

81739570 is an abundant number, since it is smaller than the sum of its proper divisors (88212686).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81739570 is a wasteful number, since it uses less digits than its factorization.

81739570 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43746.

The product of its (nonzero) digits is 52920, while the sum is 40.

The square root of 81739570 is about 9040.9938612964. The cubic root of 81739570 is about 433.9877285635.

The spelling of 81739570 in words is "eighty-one million, seven hundred thirty-nine thousand, five hundred seventy".